YOUR FOOD AND CHOLESTEROL?

Cholesterol is a dietary component that has elicited much public and scientific interest in conjunction with heart disease. Cholesterol is a soft waxy substance your body uses to protect nerves, make cell tissues and produce certain hormones. This waxy substance also plays a vital role in how every cell wall throughout the body works. Cholesterol is normally present in your blood and also in the foods we eat, like meat. Food containing saturated fats causes the body to make more cholesterol. Elevated blood cholesterol levels increase the risk of heart disease. This is because large deposits of cholesterol can completely block an artery, so the blood can't flow through. If a clot forms and blocks a narrowed artery, it can cause a heart attack or stroke.

Cholesterol regulation types and transport
In healthy individuals, cholesterol levels are maintained within relatively narrow concentration range largely by the liver which converts cholesterol to bile acids (for fat digestion), produce cholesterol receptors and impedes the body process that yields cholesterol. The cholesterol pool of the body is derived from dietary cholesterol and cholesterol produced in the liver and intestines. When dietary cholesterol is reduced, the liver and intestine increase their cholesterol output. However, very high intakes of dietary cholesterol may increase blood cholesterol levels.

Cholesterol and other fats can't dissolve in water and thus also in blood. They have to be transported in our blood inside special spherical carriers called lipoproteins. Like submarines, lipoproteins carry cholesterol from one place in the body to another. The submarines, or lipoproteins, have various names according to their density. The best known are HDL (High Density Lipoprotein), and LDL (Low Density Lipoprotein).

Low density lipoprotein (LDL) is known as the 'bad' cholesterol. LDL cholesterol level greatly affects your risk of heart attack and stroke. The lower your LDL cholesterol is, the lower your risk. When too much LDL cholesterol circulates in the blood, it can slowly build up in the inner walls of the blood vessels. In some diseased conditions such as diabetics and those with a family history of high cholesterol levels, LDL cholesterol is often higher than normal and this can be risky. Such individuals are therefore encouraged to stick to low cholesterol meals.

High density lipoprotein (HDL) is known as the 'good' cholesterol. Your body makes HDL cholesterol for your protection. HDL cholesterol travels away from the arteries and helps remove LDL ("bad") cholesterol. Having a high level of HDL cholesterol reduces your risk of heart attack. Conversely, low levels of HDL cholesterol put you at risk of heart disease. HDL cholesterol levels are often lower than normal in people with diabetes and those with a family history of high cholesterol.. This means that less LDL cholesterol can be cleared from the blood, increasing the risk of artery damage.

High levels of both triglycerides and blood cholesterol, leads to greater risk of heart disease. The risk is particularly high if you also have a high level of LDL cholesterol and a low level of HDL cholesterol. HDL helps to take triglycerides out of the blood but high levels of triglycerides prevent HDL from working effectively. Excess intake of refined carbohydrates like pastries and sugar sweetened soft drinks can raise triglycerides levels in some people.

Measuring cholesterol
It's important to know your cholesterol levels. Measuring your blood lipids level involves a simple blood test at a laboratory. It is best not to eat for 12 hours before your test. The most common measurement is total blood cholesterol. The cholesterol ratio is obtained by dividing the total cholesterol by HDL cholesterol. Some standard values are shown the table below However, different laboratories might have slightly different standards based on their equipment.

Lipid Range
Total cholesterol Less than 4 mmol/L or 200mg/dl
LDL cholesterol Less than 2.5 mmol/L or 100mg/dl
HDL cholesterol Greater than 1 mmol/L or 60mg/dl
Total cholesterol / HDL ratio Less than 4.5
Triglycerides Less than 1.7 mmol/L
Several studies have shown that a lower-than-normal level of HDL-cholesterol and a higher than-normal level of LDL-cholesterol are associated with a greater risk of having a heart attack, and conversely, that a higher-than-normal level of HDL-cholesterol and a lower-than normal LDL-cholesterol are associated with a smaller risk. In simple terms, a low HDL/LDL ratio is a risk factor for heart disease. Smoking, obesity (overweight) and sedentary life may predispose people to a heart attack and, at the same time, lower the HDL/LDL ratio. Exercise decreases the bad LDL-cholesterol and increases the 'good' HDL-cholesterol. In well-trained individuals the 'good' HDL is increased considerably.

Recommended intake and cholesterol-rich foods

Dietary cholesterol is strictly linked with foods of animal origin as all of them contain cholesterol since cholesterol is an essential constituent of animal cells. Medical nutrition experts recommend that we restrict dietary cholesterol intake to less than or equal to 300 mg/day. The recommended daily intake for meat, poultry, fish and alternatives should be 3-4 servings, which is equivalent to 6-7 match box (small) sizes of fish or meat or poultry or combined proportions of these a day and about three whole eggs a week. It is advisable to limit intake of fatty portions of meats and if possible trim off visible fat before or after cooking. You can roast, broil, grill, steam or boil these foods instead of frying.

One egg contains about 213 mg of cholesterol and 100g (about 4 match box –small sizes) of chicken or beef or mutton contains about 70 mg of cholesterol. A similar weight of organ meat- liver and kidney has 150mg of cholesterol. About 100g of brains - mostly obtained from eating sheep, goat and cattle heads carries 2000 mg of cholesterol. Therefore eating the recommended amount of meat or chicken presents no problem but excessive intake of organ meats, eggs and goat or cattle head can elevate blood cholesterol levels.

You certainly control much of the power to live without elevated cholesterol levels. Prompt attention to your diet, minimizing alcohol intake and increased physical activity will do your heart a lot of good. You can consult experts for individualized management if your cholesterol levels are high because these guidelines provided here are at best generalized.

The writer is a dietician, [email protected]